The present invention relates to filters, and more particularly to air treatment filters including a carbon media.
A variety of air treatment systems exist that remove pollutants, contaminants and harmful chemicals from air in living and work environments. Many of these systems incorporate a filter through which air to be treated passes. This filter usually includes media that removes certain contaminants from the air that passes over or through the filter. One type of media used in such filters is activated carbon.
Activated carbon is effective at removing a variety of contaminants from an air stream. Activated carbon typically has many micro-porous surfaces which facilitate the adherence of the contaminants to those surfaces, thereby removing them from the air stream.
Some manufacturers of air treatment systems have modified the activated carbon media in their filters to enhance the media's ability to remove certain types of contaminants. In a first example, manufacturers have modified individual granules of activated carbon filter media to include potassium iodide. A carbon granule so modified has somewhat improved characteristics of removing a known contaminant, formaldehyde, by catalyzing the formaldehyde to formic acid, and eventually carbon dioxide and water. However, activated carbon including the potassium iodide works well only within specific humidity ranges. In a second example, manufacturers have modified individual granules of activated carbon filter media to include potassium hydroxide which is adapted to remove acidic gases, for example, low molecular weight carboxylic acids, such as butyric acid, valeric acid, isobutyric acid, isovaleric acid and hexanoic acid, from the air stream. In a third example, individual granules of activated carbon filter media have been modified to include phosphoric acid which is adapted to remove alkaline gases, for example, putriscine, indole, skatole, methyl amine, trimethyl amine, and pyridine, from the air stream.
Although these individual granules of media remove the noted contaminants from the air stream, they fail to provide a holistic solution to removing desired contaminants. Further, multiple types of filter media are required in a single filter to ensure the desired contaminants are removed. In turn, this increases the volume of filter material, and thus the size of the filter, which can cause significant design issues for small and/or portable air treatment systems, and can also increase cost of the filter.